METHOD OF OBTAINING ZINC SULPHATE SOLUTION FOR ELECTROWINNING OF ZINC FROM SELECTED WAELZ OXIDE OF HYDROMETALLURGICAL PROPERTIES

The object of the invention is a method of obtaining zinc sulphate solution for electrolysis of zinc from selected Waelz oxide of hydrometaliurgical properties, applicable in the hydrometaliurgical process of electrolytic zinc manufacture. In the process according to the invention selected oxides of hydrometallurrgical properties from the Waelz plant are used, and the process of preparing zinc electrolyte for electrolytic zinc manufacture is carried out in three stages, wherein each of the stages is preceded by a different process of preparing process suspension. In the first stage the crude zinc oxide is treated with cold water to remove chlorine and alkali elements in a two-step counter-current operation of leaching soluble components carried out in a washing and thickening unit, wherefrom water containing alkali elements and chlorine is selectively transferred to CaCI2 manufacture. In the second stage the crude zinc oxide processed in the first stage is further treated in an autoclave at a temperature of 120-130°C to remove fluorine by treatment with Na2CO3 and/or Na2CO3 solution, after which the suspension, preferably upon thickening, is subjected to phase separation by means of filtration and washing the filter cake on the filter. In the third stage the filter cake obtained in the second stage is dissolved in the recycled acid, after which the thickened suspension is separated in a thickening and phase separation process by means of filtration and washing the filter cake on the filter, and the solution after sedimentation constitutes a zinc electrolyte for electrolytic zinc manufacture.